The present invention relates to a low sulfur, low phosphorus, low-ash consumable lubricant composition suitable for use in an internal combustion engine (ICE) and methods of using the same.
Over the last twenty years, engine manufactures have achieved remarkable reductions in particulate matter (PM) emissions by significant engine modifications. There is now a need to lubricate these new engines, while maintaining the reduced PM emissions. The low sulfur, low phosphorus, low ash consumable lubricant described herein fulfills this requirement.
Another problem associated with ICE equipped with exhaust gas after-treatment devices (e.g., catalytic converters, particulate traps, catalyzed traps, NOx traps, selective catalysts, etc.) is that the lubricating oils for such engines are used in both the crankcase as well as in high wear areas such as the valve train. Because these oils are used in high wear areas they usually contain extreme pressure (EP) agents which typically contain metal (e.g., zinc) and phosphorus in order to be effective. During the operation of the engine these EP agents decompose and the resulting decomposition products eventually enter the aftertreatment device resulting in damage to and/or impairment of the device. There is need to reduce this impact while still providing sufficient lubrication to the engine. Because of the present invention's absence of high levels of EP agents containing metal and phosphorus the exhaust gas aftertreatment device is protected from such harmful exposure.
Another problem associated with conventional ICE is that the time interval required between oil changes typically is less than the time interval required for other service items such as air filter replacements, coolant changes, brake replacements, and the like. The problem therefore is to improve the lubricant technology for these engines so that the time intervals between oil changes can be extended to coincide with other service intervals. In accordance with the inventive method, the required oil change intervals are extended due to the fact that during operation of the engine, used engine oil is continuously or periodically removed from the engine and replaced with new oil.
Another problem associated with the operation of ICE is that the exhaust gases from such engines contain the undesirable pollutant NOx. It would be advantageous if the NOx level in exhaust gases ICE could be reduced. The present invention may assist in reducing exhaust gas NOx levels because the invention is less harmful to NOx reducing catalysts.
Still another problem associated with the operation of ICE are difficulties in meeting the high demands of government regulations and consumers for low emissions and high fuel economy. One approach to satisfying these demands is the use of a highly dilute pre-mixed fuel for ignition. However, in the case of spark ignition systems, only a limited amount of dilution is tolerable before misfire and unstable operation occur. To overcome this shortcoming of spark ignition systems, “pilot” ignition systems have been used for some time. In these systems a small quantity of liquid fuel is injected into a pre-combustion chamber to allow high energy self-ignition. Direct injection pilot ignition systems using diesel fuel have proven to increase the dilution tolerance of both stoichiometric and lean burn engines. In the case of a non-diesel engine, the use of the diesel-fueled pilot ignition system requires two different fuels for engine operation. Both fuels must be available for re-fueling, and for vehicle engines, both fuels must be carried on-board. However, problems with these systems often includes damage and/or deposit build-up in the combustion chamber, after-treatment device, and/or exhaust recirculation (EGR) system, caused by the fuels used in the injection pilot ignition systems.
There is a need for lubricating compositions and systems that may be integrated with the injection pilot ignition systems of ICE in order to improve engine performance while reducing the negative impact on engine deposits and/or any after-treatment devices and EGR systems being used with the engine.
U.S. Pat. No. 6,588,393 discloses a low-sulfur consumable lubricating oil composition which comprises a synthetic base lubricating oil and from about 1% to 25% by weight of an acylated nitrogen-containing compound having a substituent of at least about 10 aliphatic carbon atoms. The sulfur content of this consumable lubricating oil is about 5 to 250 parts per million.
U.S. Pat. No. 5,955,403 discloses a sulfur free lubricating oil composition which comprises a major portion of a synthetic base lubricating oil and a minor portion of a tri(alkyl phenyl) phosphate or di(alkylphenyl) phosphoric acid antiwear agent, an amine antioxidant, a substituted succinimide rust inhibitor, and a tolyltriazole. The tri(alkylphenyl)phosphate antiwear agent is incorporated in the oil at about 0.1 to 2.0 wt % and the amine antioxidant in amount ranging from about 0.1 to 5 wt %. The succinamide is present from about 0.01 to 0.5 wt %, and the tolyltriazole from about 0.01 to 0.5 wt %.